A laser system for high accuracy positioning, either on‐axis or off‐axis, over distances up to 50 m along the beam path is described. A beam delivery system with four degrees of freedom is used for initial alignment to an accuracy of 1 &mgr;m. Proper processing of the signals from a semiconductor quadrant detector reduces the measurement uncertainties and provides real‐time response. Theoretical consideration of the beam propagation characteristics is included. Laboratory and field test results show the system gives uncertainties of less than 1% for off‐axis positions up to 1 mm.